Compaction Characteristics of Municipal Solid Waste at Open Dump Sites in Sri Lanka

The majority of municipal solid waste (MSW) generated in Sri Lanka is disposed in open dump yards. Compaction of wastes at such open dumps is the main factor that controls short-term density and resulting placement efficiency of wastes in the dumps. Maximizing waste density allows reducing dump yard space requirements. Density influences the stability of dump yards with high shear strengths. Combined moisture-density characteristics influences the hydraulics response and compressibility of wastes. Further, a lot of civil engineering construction in the Colombo city area commenced on the lands previously used for dumping of waste. Construction on already-covered dump wastes will create a lot of problems such as high settlements, slope instability, and shear failure. Four dump yard locations - Bloemandhal, Seeduwa, Negombo and Madampitiya - were selected for the study and the moisture-density relationship was studied. Some of these locations are now abandoned and the land is being used for construction activities and some are still in the process of dumping. It was observed that the compaction behavior of waste was similar to that of soils with waste; but the shape of the compaction curve has deviated from the standard bell shaped curve established for soils.